According to the prior art (e.g. DE-OS No. 23 28 929) a planetary final drive and a brake disc are arranged in a hub housing in a common oil bath, whereby the brake disc, which is pressure-medium operated, is supported, on the one hand, against a non-rotatable annular gear assembly protruding from a hollow axle in the wheel hub housing and on the other hand, against a free end of the driving shaft provided with a sun wheel.
It is also known (e.g. according to DE-OS No. 27 26 687) to provide a brake arranged between driving shaft and final drive as multi-disc brake, which is supported axially against a ring firmly connected with the rotating wheels. These known arrangements suffer from various disadvantages if applied in practice, in particular when used in the heaviest vehicles with large individually driven wheels.
To gain access to the brakes and the brake cylinder it is either necessary to jack up the vehicle and unscrew the wheel or to release several flange connections and dismantle the planetary gearing.
Also, the brake cylinder which in both cases is not protected from the intrusion of rubbings from the brake, cannot be removed without completely dismantling the wheel bearing, because it is an integral part of the inner bearing ring of the respective wheel bearing.
A further disadvantage is the considerable constructional length required, due to the use of individual tapered-roller bearings which are spaced far apart and a long threaded extension on the hollow axle protruding in the direction of the brake for fastening the wheel bearing cover. Considerable length is also needed due to the unfavorable fastening of the planet wheel carrier bolts and the additional flange seal to be placed in front of them.
The weight of the parts and their large dimensions as well as, in particular, the necessity to dismantle the wheels from the jacked-up vehicle in order to gain access to the brake, make it difficult for one man to service the vehicle.
The one-piece design of the hub housing as a planet wheel carrier also makes it difficult to design the final drive with different transmission ratios or hollow wheel diameters, but with the same wheel bearing, such as would be desirable for a wheel head in modular concept.
A disadvantage is further the lack of a certain spatial separation of the oil supplies for drive and brake so that, in an adverse situation, the gearing might be damaged not only by overheated oil, but possibly also by rubbings from the brake.